Automatic focusing device for copying or enlarging cameras and the like.



H. G. A. DUTERT.

AUTOMATIC FOCUSING DEVICE FOR COPYlNG 0R ENLARGING CAMERAS AND THE LIKE.

APPLICATION FILED JUNE 10, 1912.

1,21 1,302. v Patented Jan. 2,1917.

2 SHEETS-SHEET I.

R. G; A. DUTERT.

AUTOMATIC FOCUSING DEVICE FOR COPYING OR ENLARGING CAMERAS AND THE LIKE.

APPLICATION FILED- IU NE To, 1932.

1,211,302. Patented 1312,1917.

2 SHEETS-SHEET 2.

15 S Q 191M922 $07" UNITED STATES PATENT OFFICE.

m1 GUSTAV! sn'rnun noun, 0] PARIS, MOI.

AUTOIA'IIQ IOOUSUG DEVICE I0! COPYING OB WING C AND m Specification of Letters Patent.

Patented Jan. 2, 1917.

Application fled June 10, 1918. Serial Io. 708,878.

To an whom it may concern Be it known that I, Rani Gus'ravn An'rmm Dum'r, a citizen of the French Republic, residing in Paris, France, have invented certain new and useful Improvements in Automatic Focusing Devices for Copying or Enlarginug Cameras and the like, of which the o owing is a specification.

This invention relates to an apparatus b which two points are to be connected in sue a manner that the product of their respective distances either from one or from two other points is constant, and the invention also relates to apparatus such as photographic cameras and more particularly to enlargin apparatus.

Accor ing to this invention the two points to be connected, are joined er and to the third point from whichthe correlated distances are to be measured, by a system of pivoted links so arranged that when the whole arr ment is rotated relatively to one of the said links, the two points are constrained to demribe circumferences inverted relatively to each other with reference to the said third point.

The invention will be clearly understood from the following description and the accompanying drawings, given by way of example.

Figure 1 of'the said drawings is a geometrical figure illustrating the irrinciple on which -the invention is based. ig. 2 is a view showing dia ammatically in elevation an apparatus bu t in accordance with this invention. Figs. 3 and4 are similar diagrammatic views of an apparatus equipped with a condenser and source of light and with a second link system; and Fig. 5 is an ex lanatory dia gram. ferring to ig. 1, the two points to be connected are designated A and A and the third point is marked B. It will be seen from the theory'of circumferences inverted relatively to one and the same point, that if the straight line connecting the two points A, A to 'be connected is rotated about the third point B so that, (given that the distance of the first point A from the third is variable only between two non-infinite limits), the said first point describes such a circumference having a center C that the longest and shortest distances of the point B from the said circumference are respec- 4 and 3 respectively, movin in the tively equal to the said limits, then the second point A will simultaneously describe another circumference, the center 0 of which is on the straight line connecting the center of the preceding circumference to the point B,

The hnk system comprises three rods, 5, 6 and 7, and a base 1 formed with a guide. The lower end B of the rod 5 is ivoted in the ide, and corresponds to the xed point B, 1g. 1, which is of course the third point. The lower ends of the rods 6 and 7 (A and A respectively), slide in the guide, and constitute the two points to be connected. At their upper ends they are pivoted to the rod 5 at C and C respectively,

the distances A C, C C, B C, and A C being the same as in .1. Thus it will be seen that the two Eomts A A? are constrained to move so t at they actually describe the inverted circles of Fig. 1 relatively to the two points C and C, although in practice the base isof course the points C C move. If the distances, the product of which is to remain constant, are measured from the two movable points to two fixed points, such .as B and B, instead of to a single int such as B, then the points A and are pivoted to two slidles e and equal in length to the distances B and B B, respectively. It will readily be seen that the distance between the points A and B. will always be equal to the distance AB, and similarly the distance A B will always be equal to the distance A B, so that the two points A, and A will always move so that the product of their distances from two fixed points B and B is constant.

In the case of a photographic enlarging camera, the conditions mentioned in the last instance must be fulfilled, because in apparatus of this kind, the negative and the sensitized surface must be combined in such a manner relatively to the focal points of the lens that the product of the respective distances of the said object and surface from the said points isconstant.

In Fig. 2, the arrangement of an enlarging camera is shown diagrammatically. The points B and B represent projections of the foci of the lens 2, which is fixed to the base 1 in the guide.- The negative-carrier 3 is fixed to the slide 3 at the point A, and the holder 4 for the sensitized surface fixed, and

or print is fixed to the slide i at the point In order to describe the two circumferences inverted relatively to a point B, a circle is described with center 0 and radius such that the length Be is equal to the larger and the length to Be the smaller of the two limits of length described above. (See F g. 5.) The constant product of the two dis-- tances is then determined, (this fproduct being equal to the square of the ocal length oft the lens, as will be understood by those skilled in optics), and a line Ba is drawn, (Fig. 5), perpendicular to the diameter .00, and of a length equal to the square root of the constant product. The line a (Z is drawn per endicular to a b, and the line a e perpen icular to a c; the line (1 e represents the diameter of the required inverse circumference, and

BcXBe=aB When the negative, in the case of an enlarging camera, is illuminated by a source of artificial light and a condenser, the lens, the condenser and the source of light are connected in the same manner as the negative, the lens and the receivingl or sensitized surface of the print in the older, so that the light passing through the condenser is always brought to a focus within the lens. The system of links by which the connection is efiected is also interconnected with the first-described system, so that the light, the condenser, the negative, the lens and the receiving surface all vmove so as to be always at their proper relative distances. Constructions of this character are illustrated in Figs. 3 and 4, the former construction embodying, in addition to a link system and a pair of slides identical with those shown in Fig. 2 and similarly designated, a second link system, consisting of the rods 5,- 6 and 7, a supplemental slide 3 and a stationary member 3 The slide 3 has mounted thereon at the end B the source of light 2, and the other end 6 of this slide is pivotally connected to the lower end of the rod 7, which latter is similarly connected at its upper end 0 to the upper end of the rod 5. The lower end A of the rod 5 is pivotally connected to the adjacent end of the slide 3 associated with the first system, the opposite end A of the said slide being pivotally connected to the lower end of the rod 6, and this slide bears the negative carrier 3 and, also, the condenser 3, which are mounted thereon at the points A and A, respectively. The upper end of the rod 6 is pivotally connected to the rod 5 at the point 0, and its lower end to the adjacent end b of the stationary member 3 The aforementioned condenser3 is, there fore, located, beyond the negative carrier 3,

ii-airs and the source of light 2 beyond the said condenser. v

Inthe construction shown in Fig. 4, a sup lemental side 3", bearing the source of light 2, is substituted for the previously used slides 3 and 3 and the end b of this slide has pivotally connected to it the upper end of the depending rod 5 the lower end O of which is pivotally connected to that of the rod 5. The slide 3 bears the negative carrier 3 and condenser 3, as before, at corresponding points, and its end A-has pivotally connected to it the upper end of the rod 5 and the lower end of the rod 6. i

The arrangement of the various parts is such that the front nodal point of the condenser 3, (73. 8., that one of the nodal points which is the nearer to the print holder), is in the same transverse, vertical plane as the point A, and the slide 3 (Fig. 3), has a lengthy equal to the focal distance of the said condenser, while that of the slide 3 is equal to such focal distance plus the distance of the said nodal points. In the other construction, (Fig. 4), the condenser has a definite, predetermined focal distance equal to that between the points A A, and the slide 3 has a length equal to twice such focal distance plus the distance of the nodal points.

Having now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, I declare that what I claim is:--

1. In an optical apparatus of the character specified, the com ination, with a base, and a pair of longitudinally-movable slides mounted thereon; of a three-part link system for shifting said slides, one member of which system is pivoted to said base and the other two members to said slides and to the first mentioned member at different points in its length, the pivot point of the firstnamed member being so related to the pivot points of the second-named members that the product of the respective distances of the second-named points from the firstnamed point is constant.

2. In an optical apparatus of the character specified, the combination, with a base, and a pair of longitudinally-movable slides mounted thereon; of a link system com ris' ing three inter-connected rods pivote at their lower ends one to said base and the other two to said slides and to difierent points in the length of the rod first mentioned, the pivot point of the first-named rod being so disposed relative to the pivot points of the second-named rods that the product of the respective distances of the secondnamed points from the first-named point is constant; a lens connected to said base above and directly in line with the said firstnamed point; an object holder carried by one of the said slides; and a receiving surface carried by the other slide, the product of the distances between the object holder and one of the foci of the lens and between the other focus of the lens and the receiving surface being equal to the square of the focus of the said lens.

3. In an optical apparatus of the character specified, the combination, with a base, and a pair of longitudinally-movable slides mounted thereon; of a. link system comprising three inter-connected rods pivoted one to said base and the other two to said slides, the pivot point of the first-named rod being so disposed relative to the pivot points of the second-named rods that the product of the respective distances of the second-named points from the first-named point is constant; a lens connected to said base above and directly in line with the first-named point; an object holder carried by one of the said slides; a receiving surfacecarried by the other slide, the product of the distances between the object holder and one of the foci rods of the second-named link system connected thereto, said rods coo erating to maintain constant the product of the respective distances of the source of light and the lens from the foci of the condenser.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

RENE GUSTAVE ARTHUR DUTERT. Witrfissszc oxm, PAUL Bmnu. 

